THE STUDY OF WOOD BORERS IN CHINA-I
Biology and Control of the Citrus-root-cerambycids,
Melanauster chinensis, Forster (Coleoptera)
By K. O. VICTORIA LIEU*

INTRODUCTION
This study of the wood-borers has been conducted over a
period of more than ten years. During this period about 60
species, belonging to ten families, including Aegeriidae, Ceramby-
cidae, Curculionidae, Buprestidae and Bostrychidae have been
collected from the roots, trunks or branches of some 16 species
of trees. Whenever the material of any wood-borer was scanty,
it was preserved as a specimen only. If sufficiently abundant,
it was reared in the laboratory for study. The study of the
life history and control of the wood-borers is much more difficult
and time consuming than a similar study of a leaf feeding in-
sect. The method of studying these wood-borers has been to
make a tentative rearing of the insect in the laboratory to see
how it may be kept alive and the length of its stages, followed
by careful and thorough study of its life history, habits, and
methods of control. During these ten years altogether about
20 species of wood-borers have been reared and studied. Among
these, six species which are abundant and injurious have been
studied more seriously and completely, namely:
(1) The Mulberry borer, Paradoxecia pieli, Lieu (Lep.,
Aegeriidae). Research on this borer was carried out, first in
the Chekiang Provincial Bureau of Entomology, Hangchow and
continued to completion in Musee Heude, Shanghai, where the
writer was an Honorary Research Fellow. Before resigning from
the Bureau, because of illness in June, 1934, she had studied
the damage to mulberry trees by the larvae and developed the
methods of rearing the larvae in artificial burrows and means
of control. These have all been given in lectures to students
in the training school of the Bureau where the writer was a
lecturer concurrently. A description of the new species, in
English and the preliminary notes on the biology and control
of the same, in Chinese were written, and published in 1935.
(2) The Yellow-spotted Mulberry Cerambycid, Psacothea

*College of Agriculture, National Szeuchuen University, Chengtu, China.
Research Fellow, Board of Trustees for the Administration of the Indemnity
Fund remitted by the British Government, 1938-44.

VOL. XXVII-No. 4

hilaria Pascoe. The reserach on this wood-borer was started
in the Musee Heude, Shanghai, in the spring of 1936. On Novem-
ber 17th, due to our war of resistance in Shanghai, the writer
left for the interior. After a very arduous journey from Shang-
hai to Chungking, she resumed the studies of wood-borers, al-
though on a smaller scale. In 1938, the writer was granted a
fellowship by the Board of Trustees for the Sino-British Boxer
Indemnity Fund. Due to the scarcity of mulberry trees in
Eastern Szechuen, this work was dropped temporarily. Since
citrus fruit is one of the principal products of Szechuen, and
since the damage done to the citrus trees by cerambycids is very
serious, their study was suggested by Prof. K. S. Sie, Director
of the National Agricultural Research Bureau and Prof. F. C.
Woo, Entomologist and Plant Pathologist. A survey of Kiang-
tsing, one of the three centers of Szechuen, revealed the severity
of the damage done to citrus trees by the cerambycids and the
writer took up their study. This included the study of as many
of the species of the citrus cerambycids as she could find.
(3) The Citrus-trunk Cerambycid, Nadezhdiella cantori,
Hope. The study of this borer is now in manuscript in Chinese.
A few simple and concise Chinese papers on this borer are
awaiting revision for publication.
(4) The Citrus-branch Cerambycid, Chelidonium sp., prob-
ably new, likewise has been studied and a paper is awaiting
revision for publication.
(5) The Apple-lateral Cerambycid, Chreonoma dioica, Fair-
maire has been studied at the same time as the above and some
concise papers on the insect have been published.
(6) The Citrus-root Cerambycid, Melanauster chinensis,
Forster, one of the most serious of the citrus cerambycids is
the subject of this paper. This species is cosmopolitan, and
the adult has been described before. The systematic position
of it according to "A Study of the Longicorn Beetles of Kwang-
tung Province, S. China (Coleoptera; Cerambycidae)" by J. L.
Gressitt, is as follows: Family Cerambycidae; Sub-family
Lamiinae; Tribe Monochamini; Genus Melanauster Thomson,
1868; Species Melanauster chinensis Forster.

BIOLOGY
This species of cerambycid, in both its larval and adult
stages, very seriously attacks living citrus trees. In its larval
stage, it makes burrows first under bark and later enters the

THE FLORIDA ENTOMOLOGIST

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VOL. XXVII-No. 4

woody tissues of the lowest portions of the trunks, the roots,
and the rootlets. This method of attack is absolutely fatal to
the trees. The uprooting of some citrus trees by strong winds
at Kao-tien-tzu, Nan-nie-kuer, and some other places in Hwa-
yang-hsien, and many at Wu-chiu-toe and Hsien-feng-chang of
Kiang-tsing-hsien were all due to the work of this species of
the borer larva. As an example: a citrus tree, Citrus sinensis,
20-30 years old, in Feng's orchard at Kao-tien-tzu, (text-figure
3 e), fell down as the result of a strong push, and two more
trees of the species of Citrus tangerina, one about 5-6 years old
(text-figure 3, b) and the other about 80 years old in Lai's or-
chard, at Nan-nie-kuer, died unnoticed in about one and five
years, respectively. The adults damage citrus by eating the
petioles of leaves and the bark of twigs and branches, and the
trunks of young trees. Sprays of leaves are often seen to droop
from being gnawed at the bases, and twigs, branches, and
trunks of young citrus trees died and dry up from being deprived
of their bark (text-figure 3, a & c; text-figure 4, e).
Due to the rigid conditions in finance and the difficulties in
communication during our war of resistance, the writer has not
had any opportunity to make a thorough survey in all citrus-
growing districts of Szechuen; but is quite sure that the damage
done to citrus by this species in Szechuen is equally serious
wherever much citrus is grown. This is true not only in
Szechuen, but also in other citrus-growing provinces, such as
Kwang-tung, Kwang-si, Fukien, and Chekiang. This is evident
from the fact that soon after the booklet, "Melanauster chinensis,
Forster (Citrus-root-cerambycid)", was published in April,
1941, many letters asking for it were received. In spite of the
difficulties in communication, up to the present, about eight
hundred copies of it have been sent out to citrus growers of
some twelve provinces.
Although our final object in studying an insect-pest is to
discover methods of control, these cannot be carried out success-

Fig. 2.-a, rearing of the larvae (wood-borers) in branch-segments,
stood in water in glass jars, which are surrounded with water in earthen
vessels, or shallow pans, in the laboratory. The writer is binding up a
piece of branch segment after having examined the larva in it; b, the
longitudinal section of the upper portion of a citrus-branch-segment, show-
ing the "artificial burrow" ("a.b.") made for the borer; (times 1); and
c, the lowest portion of the trunk of a citrus tree, showing the way of
making an "a.b." in it, and the "colonization" of a borer in the "a.b."
(times 1).

THE FLORIDA ENTOMOLOGIST

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Fig. 3.-a, the young Citrus tangerina No. 66, 2-3 years old, about 3
feet high, showing the damage done to the root and the lowest portion of
the trunk by the larvae, and to the bark of the trunk and branches by the
adults; b, the root and the lowest portion of the trunk of a Citrus tangerina,
5-6 years old, from Lai's Orchard at Nan-niekuer, showing the broad and
shallow burrow made in the wood immediately under the bark which had
been detached, and the entrance-bore (EB) leading to the interior of the
wood, made by one of the larvae; c, the young Citrus tangerina No. 63, 3-4

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VOL. XXVII-No. 4

fully until the weak point or points in its life-history have been
found. As a rule, the first step in handling such a problem
must start from studying the life-history and habits.
In studying this species, many difficulties in collecting, in
rearing and investigation were met.
DIFFICULTIES IN COLLECTING. Before the writer acquired a
thorough knowledge of the life-history and habits of this species,
the collecting of the larval material was a very difficult matter
because they are wood-borers, and only 16-20 mm. long, and,
throughout their existence, normally concealed, as are also their
pupae and adults in their burrows in the woody tissues of
the lowest portions of the trunks. They can be obtained only
by chiselling, cutting, sawing, splitting, or even uprooting of
a tree. Consequently, many difficulties had to be contended with,
particularly in obtaining the permission from the owners of
citrus orchards who, very often, did not allow their citrus trees
to be touched with tools, especially during the period from the
latter part of April, when citrus begins to bloom, to some time
in December, when the fruits are ripe and ready for harvest.
Between December and April, when the temperature is very
low, most of the borers are still hibernating. To make the
owners of citrus orchards understand the purpose required much
effort. Besides, if a borer has already burrowed deeply into
the trunk, or has burrowed downward into the root, it would
be unwise and unreasonable to damage a tree, or even kill it,
for simply getting one or two borers. Moreover, in chiselling
and cutting, or in sawing and splitting, a borer is very apt to
be injured by the tools. Therefore a whole day spent in collect-
ing usually resulted in obtaining only a few borers, of which
the living ones for rearing were still fewer.
METHOD OF STUDY. The most difficult period in rearing a
cerambycid, which attacks living wood, is during its larval

years old, about 4 feet high, showing the damage done to the root and
the lowest portion of the trunk by the larvae and to the bark of the trunk
and branches by the adults; d, the trunk and the root of an old Citrus
tangerina, 70-80 years old, showing the combined damage by the larvae
of this species and those of the citrus-trunk-cerambycids (N. cantori, Hops) ;
e, the root and the lowest portion of the trunk of a Citrus tangerina from
Feng's Orchard at Kao-tien-tzu, showing the damage done by the larvae;
and f, the longitudinal section of a lemon branch (CT No. 12), branching
from the short trunk of a lemon tree at a very low point, showing a larva
hibernating in the upper portion of its burrow, with a "plug" of wood chips
below its head for protection-(times 1).

THE FLORIDA ENTOMOLOGIST

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Fig. 4.-a, whitewashing of the citrus trees for control tests against
both this species and the citrus-trunk-cerambycids (McH), with the writer
standing among her trees inside the college; b, whitewashing of the citrus
trees in the Lion-hill orchard of this college, for the same purpose, taken
immediately after the work is done; c, the home-made brush for applying
the whitewash paste on trees; d, the young Citrus grandis No. 6, about 5

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VOL. XXVII-No. 4

stages, because this stage of a cerambycid usually lasts very
long, from several months to 3 or 4 years.
In the laboratory, whenever a cerambycid larva (borer) of
any species is collected, it is first examined with a hand lens
to see if there is any parasitic egg or larva on its boy. Then,
it is "colonized" in an "artificial burrow" in a segment of a
branch.
From experience in studying the wood-borers, Paradoxecia
pieli (a mulberry Aegeriid), Psacothea hilaria (a mulberry
Cerambycid), and some other cerambycids, the writer has de-
vised, after many trials, a very successful method of rearing
them, i.e., "colonization" of wood-borers in "artificial burrows",
which method she is employing for rearing the borers of this
species of citrus cerambycid.
In rearing, the borers of each species collected are divided
into two groups, one group is "colonized" in branch-segments
in the laboratory, and the other "colonized" in thick branches or
trunks of trees in the field. The methods of "colonizing" a borer
in a branch-segment and in the trunk of a citrus tree consists
of six steps:
1. Split a segment of a branch, about 20 cm. long and thick enough to
contain the borer, longitudinally into two halves of unequal size;
2. On the surface of the longitudinal section of the larger half with
a sharp chisel, cut the 4 sides of a rectangle, whose upper side is
about 1 in. from the upper end of the segment, and pare off the
woody tissues of the rectangle to make a burrow, just big enough
to contain the borer to be colonized (see text-figure 2, b). Thus,
an "artificial burrow" ("a.b.") is finished;
3. Place the borer, head-up or head-down, according to its original
position, in the "a.b.";
4. Fit the smaller half of the branch-segment upon this larger one,
and bind them together against the "a.b." with a white ribbon;
5. Apply a label, with the number of the borer and the date of "coloniz-
ation", on the bark of the smaller half of the segment just a little
above the ribbon; and
6. Finally stand the segment in a little water in a glass jar, which is

years old, removed from the cage to show the damage done to the lowest
portion of the trunk by the larvae, hatched from the eggs deposited there
by the females in the cage; e, the young Citrus sinensis No. 16, 6-7 years
old, removed from the cage to show the damage done by the larvae and
adults while inside the cage; f, the young Citrus tangerina No. 10, 4-5 years
old, whitewashed and placed inside the cage for studying control test; and
g, the lowest portion of a citrus trunk, showing the slits made by the female
adults and the eggs deposited under the bark-(times 1).

THE FLORIDA ENTOMOLOGIST

again stood in a shallow earthenware vessel of water (see text-
figure 2, a), and record it in the record-book for this species.

To "colonize" a borer (say about 20 mm. long) in the trunk
of a living tree consists of eight steps:
1. Choose a healthy citrus tree, and apply a wood label with a number,
such as Citrus tangerina No. 5;
2. Chose a position on the lowest portion of the trunk, a few inches
above the ground. On the bark here, cut the right, left, and lower
sides of a rectangle, about 25 mm. long and 8 mm. wide, and peel
this slice of bark up, and fasten it against the trunk with a cord;
3. On the cambium layer of the trunk at this place, cut the right, left
and upper sides of a rectangle, a little shorter and narrower than
the first one, and peel the thin slice of woody tissues down, and
fasten it, also against the trunk;
4. Then, carve a still shorter and narrower rectangle at the same place,
and pare off the woody tissues of this rectangle to make a burrow,
just big enough to contain the borer to be "colonized". Thus, an
"artificial burrow" ("a.b.") in the trunk is finished (see text-
figure 2, c);
5. Place the borer in its original position, in the "a.b.";
6. Raise the slice of wood into position, and lower the slice of bark
down as well;
7. Wrap this part of the trunk with a piece of oil-paper or glossy-paper,
and wrap it with layers of bark-fibers of Chinese hemp (treated)
to prevent the drying of the "a.b.", the entrance of rains, and the
attacks of ants;
8. Finally, record it in the record-book on "Colonization of Wood-borers
in Citrus trees."

The borers "colonized" in the segments of branch need much
more care, work, and time than those "colonized" in the trees;
because the segments of branches, though standing partly in
water, still tend to become dry and have to be replaced with
fresh ones frequently; how often depending on the weather,
and the condition of the borers.
As soon as a larva has burrowed to the lower end of a seg-
ment, or the segment has become dry, it must be replaced.
Furthermore, to protect the borers from being attacked by
a species of small red ant (a Monomorium sp. as determined by
Dr. M. R. Smith), the whole segment is stood in water.
DIFFICULTIES IN INVESTIGATIONS. The branch must be
examined every day or two, (1) to observe the presence of any
wood-dust or frass and (2) or any new boring done and these
observations are recorded. Then, the segment is untied, opened,
and examined, and the following points noted and recorded,
(1) the appearance of the borer, (2) in what direction its head

VOL. XXVII-No. 4

points, (3) how it burrows, (4) how long it has burrowed,
(5) how many burrows it has made, (6) the length of its body,
(7) whether there is any "plug" made, (8) whether there is
any exuviae or parts of exuviae, etc. Before the halves of the
branch-segments are closed up the inside is cleaned and wiped
with a dry towel to prevent any interference by factors from
outside, the glass jars and earthenwares cleaned, and the water
in them changed.
Although the borers "colonized" in trees are not so trouble-
some as those "colonized" in segments of branches, they have
to be observed and recorded every day.
From these investigations, the growth, moltings, habits,
hibernation, transformation, damage done to the interior of the
wood, and the methods the borers use for self-protection can be
studied. From the investigation of the borers "colonized" in
trees, the actual lengths of the larval, pupal, and adult stages,
the periods of hibernation and transformation, and all the phe-
nomena and habits connected with these can be studied with
exactness.
As to the adults, pairs of males and females are reared in
big wire cages supplied with young citrus trees planted in pots
for food, where oviposition, habits, injury, etc., can be studied,
for about two years.
A. MORPHOLOGY
1. THE EGG. The egg (text-figure 1, a) is elongate, sub-
cylindrical, and tapering towards both ends, varying very slightly
in form. The surface of the eggshell is smooth. The color,
when first deposited under bark, is creamy-white; but towards
hatching gradually turns yellowish-brown. The average of 20
eggs was 5.5 mm. when measured, and the average diameter
across the middle 1.7 mm.
2. THE LARVA. The larva (figure 1, b) is a legless grub, about
5 mm. long when first hatched, and the largest ones are about
52 mm. long when full grown, measured from the anterior mar-
gin of the prothorax to the tip of the abdomen. Its color is
creamy white except some yellow, chitinized patterns on the
prothorax.
The head is dull yellow brown in the anterior half, and chest-
nut brown near the oral margin. It is moderately depressed
with the sides parallel. The antennae are very short, and con-
sist of three segments each. The ocelli, one on each side, are

THE FLORIDA ENTOMOLOGIST

ventro-lateral to the antennae. The mandibles are black, and
are very strong cutting tools. The labial palpi are two-jointed;
and the maxillary palpi three-jointed.
The width of the prothorax is about twice that of the head;
and its length about one and one-half times that of the meso-
and meta-thorax combined. The yellow chitinized patterns on
the dorsal, ventral, and lateral sides of the prothorax, and the
ampullae on the dorsal and ventral sides of the meso- and meta-
thorax and the first abdominal segment, as shown in the text-
figure 1, c and d, are probably characteristics of these species,
or at least of the genus.
The abdomen consists of ten segments, which are nearly
equal in width, but slightly constricted between the 6th, and
7th segments. The segments vary in length. The 1st and 2nd
are very short; segments 3 to 8 are each about twice the length
of the 1st, or the 2nd; segment 6 is the longest and 10 one of
the shortest. The larva has 9 pairs of spiracles. The first pair
is located on the sides of the prothorax, also visible on the ven-
tral side; and the remaining pairs are on the sides of 1-8. The
ampullae on the dorsal and ventral sides of abdominal segments
1-7 are similar to those of the first abdominal segment as shown
in the text-figure 1, c and d.
3. THE PUPA. The Pupa (figure 1, e) varies from 27 mm.
to 38 mm. in length. The head is large with the front directed
obliquely inward below, with the labial and maxillary palpi,
directed caudad, almost parallel to the axis of the body. The
elytra only partially cover the wings; both are curved around to
the ventral surface of the body. Ventrally the tips of the elytra
approach each other more than those of the wings; they do not
meet but leave a space for the tarsi. The wings actually lie
against the sides of the body, with the tips pointing posteriorly.
The pro- and meso-thoracic legs are sharply bent at the femoro-
tibial joints of the pro- and meso-thoracic legs, and then coil
ventrally to lie over the elytra and wings.
The first pair of spiracles, located on each side between the
pro- and meso-thorax are also visible from the ventral side. The
abdominal spiracles 1-5 are conspicuous on the sides, while the
remaining 3 pairs are degenerate.
At the tip of the abdomen, there is a chitinized process, which
is curved dorsally to form a V, when viewed from the caudal
end with the ventral side up. Considering the absence of this
process from the pupae of several other species of Cerambycids,

VOL. XXVII-No. 4

it is most probably an important characteristic of this species.
On the dorsal side of each abdominal segment 1-4, there are
two groups of thick setae, one on each side of the segment; they
are used for locomotion.
4. THE ADULT. The adult is large and stout; shining black
with somewhat rounded spots of white pubescence on the elytra.
The two sexes (see text-figure 1, f and g) are very similar, differ-
ing only in size, in the length of antennae, and in the structure of
genitalia. The body length of males is 22-38 mm., and that of
the females 24-40 mm. The width of males across the bases
of elytra is 9.5-11.5 mm., and that of females 11.0-13.8 mm.
The head is vertical. The antennae are very long in both sexes.
They consist of 11 segments each, and are setaceous in form.
In males, the distal end of the 6th segment reaches to, or a
little beyond the tip of the abdomen; while in females, to the
distal end of the 8th segment does so. The tip of the abdomen
of the males is entirely covered by the elytra, while that in
females is more or less exposed. Since this species is not new,
no further description of the adult is necessary.

B. LIFE HISTORY
While the writer was waiting in Chungking for a location
for research to be arranged by the Board of Trustees, she went
on with her study of the termites and the mulberry cerambycid
(an Apriona sp.). When, on January 12, 1939, a notice was
received informing her of the location she started early next
morning for Chengtu, and arrived at this college on January 17.
Usually, to make a study of an insect pest, one should start
in the late spring or summer, when most material is available.
Since January and February are the coldest months of a year
in Chengtu, neither appearance of the adults nor activities of
the larvae of any cerambycids can be expected. The anxiety
for material urged the writer to make early explorations into
the citrus districts in the suburbs of Hwa-yang-hsien, such as
Dong-chia-shan, Kao-tien-tzu, Lion Hill, etc., for damaged trees,
with the hope of getting some larvae, pupae, or hibernating
adults of some cerambycids by sawing and splitting the branches,
trunks, and roots of the trees and of getting some idea of how
a cerambycid borer enters the trunks and roots, how it lives
and prepares for its emergence, and how the wood inside is
actually damaged. The first collecting trip made was to Dong-
chia-shan on January 29, and was followed by several others

THE FLORIDA ENTOMOLOGIST

in February. The results obtained at first were rather dis-
appointing. After having made several trials, she was able to
find in an orchard at Dong-chia-shan, a very large dying citrus
tree between 70-80 years old, and after much explanation and
persuasion to obtain it from the owner on March 1, 1939 (see
text-figure 3, d).
This large tree was a Citrus tangerina. Its main root (9
and 10 in the figure) was at a depth of about a foot and a half.
It trunk, 6-8 inches in diameter (1-8 in the figure), was about
5 feet high, with three thick branches ranging from 8 to 10
feet long. The root and the trunk had been badly burrowed by
the larvae of this species and the larvae of the citrus-trunk
cerambycids, Nadezhdiella cantori, as proved later through rear-
ing. The tree was almost dead, having only a few smaller
branches bearing some old leaves of the previous year. The
poor appearance of the root and trunk of the tree, as shown in
the text-figure 3, d, may well represent the general condition
of citrus trees damaged by the larvae of the two species of
cerambycids at Wu-chiu-toe and Shien-feng-chang of Kiang-tsing-
hsien, Chao-chia-tu of Kin-tan-ksien, and all citrus-growing dis-
tricts of Hwa-yang-hsien, which the writer has visited.
After this dying tree had been brought back to the laboratory,
with the help of the late faithful workman, Wang-soo-yuin, its
branches were sawed into many segments, and the root together
with the trunk was sawed into ten portions and later split into
many pieces. The root, the trunk, the branches, and the twigs
were thoroughly and carefully re-split into many smaller pieces
and examined. Since this tree was dying, it had of course, been
deserted by most insects, except a few species of wood-borers,
which might have entered it some months or years before. These
were:
(1) A larva of this species found in the root; (2) a hiber-
nating adult of Nacezadiella cantori in its pupal-cell in a thick
branch; (3) a larva of the citrus-branch cerambycid, Cheli-
donium sp., in a thick branch; (4) a few buprestid larvae under
the bark of the trunk; (5) a few red-banded larvae of cossidae
(?) in branches; (6) a few small creamy-white larvae of
cossidae (?) in smaller branches; and (7) some cicada's eggs
in the few living twigs. These larvae and the hibernating adult
were either reared or preserved, and the affected parts kept as
specimens. The entire examination of this big tree required
more than two weeks.

VOL. XXVII-No. 4

Though the time spent in examining this big citrus tree
seemed great and the insects obtained few; from the point of
view of research, what was obtained from it was really of much
importance, because at the beginning of her research with the
different species of citrus cerambycids, everything was unknown
to the writer and she obtained some information which helped
her much in collecting and studying these species.
Before one has acquired a thorough knowledge of the life
history and habits of this species, the collecting of its larvae
is very difficult. Therefore, the study of this species began from
collecting the adults in May and June, 1939.
Since the larval stage of this species (Melanauster chinensis,
Forster), is the most difficult to be reared of all the species of
cerambycids studied during the past nine years, the study of
its life history has been repeated twice, first in the year 1939-40,
and again in the year, 1940-41.
THE STUDY OF THE LIFE HISTORY OF Melanauster chinensis,
Forster in 1939-40. From May 28 to June 26, 1939, ten adults
were collected from citrus trees. Of these only two were males.
The first one collected on May 28, 1939, was a male. It was
reared in a big glass jar, covered with a board, and supplied
with a segment of a branch and a spray of leaves for testing
its food habits. The second adult, collected on June 6, was a
female, which was immediately mated with the first male in the
glass jar and the segment of a branch and the spray of leaves
were replaced with fresh ones. The beetles were seen to eat
the leaves, petioles, and the bark of the spray and the segment
of the branch. Two days later, the segment was examined, and
two T-shaped incisions were found on the bark near the lower
end of the segment, and two eggs were found under the bark.
one at each incision.
On June 8, the two adults were transferred to a large wire-
gauzed cage, and supplied with a young citrus tree planted in
an earthen pot and a few sprays of leaves for the purpose of
studying their food habits, mating, egg depositing, the damage
inflicted, etc. This small tree was a Citrus tangerina, 2-3 years
old, about 3 feet high and with a trunk diameter of about 0.6
inch (see text-figure 3, a). Between June 8 and 13, three in-
cisions were found on the bark at the basal portion of the trunk.
Since this tree was very small, it was removed from the cage,
and another small one supplied. But, no more incisions were
found.

THE FLORIDA ENTOMOLOGIST

On June 13, a second male and a second female were col-
lected. They were treated in the same manner as the first pair
on another Citrus tangerina, 3 or 4 years old, about 4 feet high
and with a trunk diameter of about 0.8 inch (text-figure 3, c).
Since the first object was to get as many eggs as possible, the
four females, collected on June 16 and 24, were all reared in the
same cage with the only remaining male. On June 20, this
small tree was examined and seven incisions were found in the
bark at the lowest portion of the trunk. This tree was removed,
and three small trees were used in succession. In addition,
eight segments of a branch were added in the cage in succession.
Between June 13 and July 7, 13 incisions were made on the tree
trunks and the segments.
The exudation of very fine wood dust and fibers indicated
the hatching of the eggs. Since the trees were dying, it was
feared that they mould be insufficient for keeping the larvae
alive. Therefore, the trees were uprooted, sawed, and split, as
were also the segments. Sixteen larvae were picked out of the
trees and segments between October 6 and 15. Of these 16
larvae, 4 injured and 1 good one were preserved as specimens,
5 were "colonized" in segments of branches and 6 were "colon-
ized" in trees. The segments and the 6 young trees with the
larvae were all kept under observation in the author's labora-
tory.
The 5 larvae in segments died in from two weeks to 4 months.
Of the 6 larvae, "colonized" in small trees, 2 died and 4 succeeded
in transforming into adults, 3 males and 1 female. One adult
emerged on June 8, others on June 25 and June 29, showing
that this species has but one generation a year.
THE STUDY OF THE LIFE HISTORY IN 1940-41. The male adult
emerged at about 6 a.m., June 8, 1940, from an almost circular
bore, whose diameter was about 10 mm. made on the trunk of
a Citrus tangerina at about 10 inches above the ground, and
was caught inside the wire sheath wrapped around the tree
trunk from May 20. It was taken out and liberated in a small
wire-gauzed cage and fed with a segment of a branch bearing
a few sprays of leaves. It ate the leaves, petioles, and bark.
The female emerged between 1:10-2:02 p. m. on the same day,
from a circular bore, whose diameter was about 9 mm. made
on the trunk of the Citrus tangerina at about 101/ inches above
the ground, and was caught inside the wire sheath as in the
case of the male. These two adults were immediately mated

VOL. XXVII-No. 4

in a large wire-gauzed cage, supplied with a small tree, plus 1
or 2 sprays of leaves every day (for food).
Between June 8 and June 16, one or two matings were
noticed every day and sometimes three matings a day, but not
a single oviposition was made by the female. Both the male
and the female gnawed at the leaves, petioles, and bark of the
trunk so often that the small tree was entirely deprived of its
bark and leaves. The adults sipped water from the wet mud
in the pot.
Another small tree of Citrus grandis (text-figure 4, d) was
placed in the cage on June 16. When it was examined on June
19, 3 incisions were found at the basal portion of the trunk.
This was removed from the cage and a third tree of Citrus
tangerina was again substituted. Although matings were seen
nearly every day from June 16 to July 5, only 3 ovipositions
were made by the female on the last tree before her death on
July 6, 1940.
Six ovipositions were made on the two trees (C. gandis and
C. tangerina) and two full-sized eggs were left in the female's
abdomen after death. Therefore, the total number of eggs this
female could have produced was 8. None were lost because as
soon as the female had emerged she was kept in a wire-gauzed
cage.
The length of the 4 matings observed in this cage were 38,
46, 55, and 70 minutes. This species does not deposit eggs soon
after mating. The pre-oviposition period is rather long, and
may take 1-2 weeks. Although many matings had been seen,
only one oviposition was observed.
OVIPOSITION. On June 26, 1940, at about 6 a. m. this female
cut the bark with its mandibles at the base of the trunk of the
tree, Citrus tangerina, first vertically and later horizontally, to
make a T-shaped slit, at about 2 inches above the mud. This
took about 6 minutes. After the slit had been made, she turned
her head upward and inserted the ovipositor into this slit, apply-
ing force for some 38 minutes, depositing one white egg in a
vertical position under the bark (figure 4, g).
This female died on July 6, and the male on July 8, giving
28 days for the life of the female and 31 days for that of the
male.
Besides this pair of reared adults, another 10 pairs, collected
from citrus orchards in the suburbs of Hwa-yang-hsien in June
and July, 1940, were kept separately in several large wire-

DISCUSSIONS :
(1) The number of eggs deposited in C. sinensis was 8. This
tree was not split, but left standing intact in the laboratory.
Although all the 8 eggs hatched, only one larva was secured
from under the bark and "colonized" in a small citrus tree about
3 years old, and the remaining larvae were left untouched. On
May 30, 1941, a male adult, body length 22 mm., was caught in
a wire sheath which had been applied on the trunk some 10
days before. It was killed and preserved as a specimen. The
emergence of this adult again shows that this species of citrus-
root cerambycid, Melanauster chinensis, Forster, has but one
generation a year.
This tree was broken at the basal portion of its trunk by a
slight touch by a small boy one day in September, 1941. When
it was examined, it was found that:
(i) A broad and shallow half-formed gallery made by the
larvae on the outside, extended upward from the base of the
trunk, for about 10 inches (or 250 mm.) ;
(ii) A burrow, in the center of the trunk extended up-
ward from the base about 3.2 inches (or 80 mm.) ;
(iii) Five or 6 partly connected shorter burrows, viewed
from the under-surface of the basal portion of the trunk;
(iv) Five or 6, partly connected short burrows in the
root, connected with those in the basal portion of the trunk;
(v) The root with the rootlets, about 6 inches (or 150
mm.) long, had also been severely burrowed;
(vi) A single big, circular emergence hole;
(vii) That no more larva, pupa, or adult were found in
the tree proves very well that some of the larvae hatched

VOL. XXVII-No. 4

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THE FLORIDA ENTOMOLOGIST

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VOL. XXVII-No. 4

must have been killed by other larvae while others must
have been eaten by ants; and
(viii) The damaged condition of the tree shows that it
must have died since the previous winter.
(2) Sixteen eggs were deposited in citrus trees (excluding
C. sinen. No. 16) ... ..............--------------------. 16
Twenty-five eggs were deposited in C. segments-..-... 25
Two eggs were deposited in willow segments...-----... 2
Three eggs were deposited in mulberry segments .. 3
(3) Of these 46 eggs laid by the 9 females, 5 failed to hatch,
6 were destroyed during splitting, 2 were given away for ex-
tension work and 3 larvae were preserved, leaving 30.
In addition 1 larva was picked out from C. sinensis, 3 from
C. grand. and 3 from C. tang., making a total of 37 larvae to be
colonized for study.
(4) The adults do not deposit eggs in citrus trees in poor
condition, as in the case of the female of the fourth pair, though
it had 16 eggs in its abdomen.
(5) The adults, while confined in the breeding cage, ate the
leaves, petioles and bark of citrus trees, but never those of either
willows or of mulberries.
(6) The adults never deposited eggs in the whitewashed
segments of citrus trees in the cage of the second pair, nor in
the whitewashed citrus trees in the 2 cages of the sixth and
seventh pairs and of the eighth pair. One female did deposit
3 eggs in a whitewashed C. grandis, but only at places where
the whitewash had been washed away by heavy rains, which
occurred almost every day from June 27 to July 1, 1940. For
the compositions of the whitewash used in the different tests
and the detailed discussions of the results see-under heading
"Control".
Colonization of Larvae in Trees and Branch-Segments in the
summer of 1940. Of the 37 larvae to be colonized for study, the
group (A) of 15 larvae were colonized in 15 citrus trees, 6-16
years old, one in each; the group (B) of 15 larvae were colonized
in 15 segments of citrus branches about 200 mm. long, one in
each; 5 larvae were colonized in 5 small mulberry trees, and
the remaining 2 larvae were colonized in 2 small willow trees,
as follows:
GROUP A. Since the larvae were not picked out of the citrus
trees and segments at the same time, and their sizes varied
much, the method of colonizing them in the basal portions of

For studying facundity alone. 40 females were collected in the summer of 1940 and
dissected. The numbers of eggs in the abdomens of the females varied from 6 to 20.
Again, 10 females were dissected in the summer of 1941, and the numbers of eggs in the
abdomens of the females varied from 8 to 19.

citrus trunks was modified a little. Those larvae, whose body
lengths were longer than 16 mm., were colonized in "artificial
burrows" (a.b.) made in the wood; while those, which were
shorter than 16 mm., were colonized in "a.b." immediately under
the bark, so that they could continue to feed in the green, sappy
portion of the inner bark.
The smaller larvae, whose sizes varied from 5 mm. (newly
hatched ones) to 16 mm. long, were 9 in number. About one
month after the "colonization", the "artificial burrows" were
opened and examined. Two larvae were found mouldy and de-
caying in the "a.b.", three had been eaten by ants (only head

VOL. XXVII-No. 4

capsules left), while the remaining four had survived very well,
because they had grown big enough to bore into the wood and
lived in a normal condition. Whenever a larva is about to
moult, it usually is hard for it to adjust itself to a new environ-
ment, and the wet condition under the bark would very easily
cause moulding. The gnawing of the inner portion of the bark
by the larvae always causes the outer portion of it to become
very thin, so thin that after being dried by the weather it would
break and thus give inlets for the invasion of ants, especially
the "small red ants" (a Monomorium sp., as determined by M.
R. Smith).
The larger larvae, colonized in "a.b." in the wood, were 6 in
all. About two months after "colonization", the "artificial
burrows" were opened and examined. One larvae still remained
in the "a.b.", without any signs of activity being shown, while
the remaining five had burrowed well into the depths of the
wood and could not be seen at all. That larva, remaining in
the "a.b." was 26 mm. long when it was colonized; but when
examined its body length had contracted to 19 mm.
After the middle of May, 1941, the citrus tree which had
the larger larva colonized in it was uprooted, sawed, and split
to look for the emergence of the adults. The larger larva had
transformed into a pupa on May 16, 1941. Since no emergence
of the adults occurred until June 26, another citrus tree was
uprooted, sawed, and split, and again a pupa was found in it.
Since no pupa of this species had been obtained, these two pdpae
were preserved as specimens. The citrus trees were observed
two or three times every day. On June 29, 1941, an adult was
seen to enlarge a bore for emergence. But, it did not succeed
in emerging, because the bore was made against the layers of
Chinese hemp fibers, used for fastening the artificial burrow.
Since the layers of Chinese hemp fibers were not so easy to be
gnawed as the bark of the trunk, the adult was killed.
Between July 21 and August 2, 1941, four more adults
emerged in succession. On August 2, the remaining three trees
which had been colonized, each with a larva, in the summer of
1940, were uprooted, sawed, and split to discover the fate of the
larvae. It was found that one larva had already transformed
into an unhealthy pupa; one had died, and the last one was still
living, although unhealthy, in the "a.b.", due to the poor condi-
tion of that tree. This last larva was again taken out from its
burrow, and re-colonized in a better tree. It did not transform

THE FLORIDA ENTOMOLOGIST

into a pupa, until sometime in June, 1942, but died in a poor
condition. This shows that if a larva fails to emerge as an
adult in one year's time, it will die.
In short, in the Group A, out of 15 larvae colonized in the
basal portions of the trunks of 15 citrus trees, five adults and
three pupae were obtained in one year's time.
GROUP B. Since the 15 larvae of this group were also of
different sizes, they were colonized in 15 segments, one in each,
either in the "a.b." inside the wood or in the "a.b." under the
the bark, according to their sizes. Each segment was stood in
a glass jar, with a little water. These jars were, in turn, stood
in earthenware dishes with water to protect the larvae from
the small red ants. These are shown in the text-figure 2, a.
Since the segments very easily get too dry, for the larger
larvae colonized in the "a.b." inside the wood, they also had to
be replaced with fresh ones every 2 or 3 days. Although much
time and care had to be spent on this group, they did not give
as good results as the larvae (borers) of Paradoxecia pieli, Lieu,
Psacothes hilaris, Pascoe, and several other species of Ceramby-
cids. The only reason lies in the fact that the larvae of this
species feed in the green, sappy portion of the inner bark, over
too long a period. If they were poorly fed in their earlier larval
stages they could-not recover sufficiently to undergo the remain-
ing transformations.
From this group, starting also with 15 larvae, only two
larvae succeeded in transforming into adults.
The 5 larvae colonized in 5 mulberry seedlings and the 2
in 2 willow seedlings all died in 2 or 3 months, because the trunks
of these seedlings available for use were not thick enough.
The results obtained from studying the life history are as
follows:
1. THE EGG STAGE. From the two columns, "Eggs deposited"
and "Eggs hatched", in Table 1, the length of the egg stage, that
is, the incubation period, is from about one week to three weeks
in June, July, and August. Whenever the room temperature
is between 75 and 90 degrees F. or higher, the embryos in the
egg shells develop more readily than when the room temperature
falls below 75 degrees F.
The First Weak Point in the Life-Cycle. So far as natural
enemies are concerned, the egg stage is the easiest to be attacked
by ants, because whenever a cut is made on the bark of a citrus

VOL. XXVII-No. 4

trunk, a little sap oozes out. This oozing attracts the ants which
may be able to reach the eggs.
2. THE LARVAL STAGE. The legless larva is about 5 mm.
long when first hatched in June, July or August (the summer
months). It feeds at first in the green, sappy portion of the
inner bark of the basal portion of the trunk of a citrus tree
for about 2 months and then begins to bore into the wood.
The rate of growth is not uniform. One larva may grow much
faster than another. For example: The six larvae, hatched
from the eggs deposited under the bark in the basal portion
(about 2 inches long) of the trunk of a Citrus tangerina in the
same cage between June 13 and 20, 1939, measured, respectively,
13, 18, 27, 32, 39 and 40 mm. in length on October 11, 1939,
when they were picked out of the basal portion of the trunk and
of the root. The larvae hatched in the summer of 1940 showed
similar variation.
The larvae, picked out of the wood through sawing and split-
ting, were usually larger. Their body lengths were always
longer than 16 mm. and a few may be as long as 17, 18, or 19
mm. and still remain under the bark. As a rule, when a grub
grows to the length of over 16 mm., its mandibles are getting
strong enough for it to bore into the woody tissues, and it does
so. The entrance bore into the wood made by any of the grubs
is shown in the text-figure 3, b.
While the grubs still remain under the bark, the careful
paring away of the dry outer bark will disclose them, surrounded
by packed masses of wood-dust, in their half-formed galleries
which groove both the bark and the sap-wood. This deprivation
of the 6 citrus trunks of their bark is fatal to the trees (text-
figure 3, b).
The grubs burrow irregularly inside the wood, sometimes
upward or downward, and sometimes right or left. That the
burrows are limited to the roots and the basal portions of the
citrus trunks is shown by the two small citrus trees in the text-
figure 3, a and c. The external view of the damage done by the
grubs of this species can be seen from the text-figure 3, b, d and
e; and figure 4, d and e. The total length of the burrow made
in the wood by any one of the grubs throughout its larval stage
is about one and one-half feet, as shown in the burrows made
by many larvae. Though the burrows made by the grubs are
not very long; they are fatal to the citrus trees.
Self Protection. The burrows are irregular in form; some

THE FLORIDA ENTOMOLOGIST

broad and some shallow, but the cross-sections of the burrows
are always oval in shape. Each burrow has a few openings for
the exudation of frass, and probably also in preparation of an
exit. For self-protection, the openings and except for that
portion which the grub occupies the burrow is always filled up
with wood fibers and wood dust (see text-figure 3, f). There-
fore, the grub is perfectly safe in the depth of the wood, where
no attacks by either man or ants can reach it, unless the tree
is uprooted, sawed, and split.
A grub, hatched in the middle of June, would enter the
wood about the middle of August of the same year. In the wood,
it continues to burrow until it grows to about 40 mm. long. In
the first part of November, when the temperature (in room)
falls to about 55 degrees F., it begins to prepare for hibernation
(text-figure 3, f). Some grubs, which hatched later and entered
the wood still later, continued to burrow in the wood, sometimes
until December. When the temperature (in room) falls to about
50 degrees F., they begin to resume their activities inside the
wood. When one has completed its growth in the spring and
is about to pupate, it excavates a pupal chamber like a "dead-
lane" in the same way as for hibernation, and plugs the entrance
with wood fibers and wood dust, which are packed so tightly
(probably with some sort of secretion from their mouths) that
they are not easy to remove even with a pair of forceps. While
the grubs are feeding and burrowing under the bark and inside
the wood throughout their laval stage, they do not often make
openings and they exude the wood dust and frass only occasion-
ally, therefore, their destructive activities are very apt to be
overlooked.
The Second Weak Point in the Life Cycle. Fortunately, there
is in its life cycle, another weak point to the attacks of man.
While the grubs are burrowing under the bark during the first
two months, they can be killed very easily by mechanical methods
(see under "Methods of Control").
The Third Weak Point in the Life Cycle. The larvae of this
species are carnivorous and canabalistic, one always killing the
other whenever two of them meet.
While the larva is living under the bark and inside the wood,
it undergoes several moults (the exact number of which cannot
be given now, but must be checked again sometime in the future).
A larvae is always active, except before each moult, when it
lies quiescent for a few days, corresponding to the "sleeps" of

VOL. XXVII-No. 4

a silkworm. After it has cast off its last larval skin, it becomes
a quiescent pupa. The larval stage lasts for about 10 months.
3. THE PUPAL STAGE, INCLUDING THE PRE-ADULT STAGE.
The pupa is creamy white and quiescent at first. It moves the
tip of its abdomen very often while it is growing darker and
darker in color. Before it is going to cast away its pupal skin
to transform into a pre-adult, it becomes quiescent again. The
pre-adult is also quiescent at the beginning of its transforma-
tion. It takes a week or two to reach maturity and begin its
activity by scratching away the wood dust and wood fibers at the
entrance of the pupal chamber and enlarging an old opening
into a somewhat circular one for its emergence. This stage
lasts for about one and one-half months.
4. THE ADULT STAGE. As soon as an adult has emerged,
it flies away to a citrus tree and feeds on the petioles of leaves
and the bark of twigs. They are very active under sunshine,
flying here and there. When resting on the bark of twigs,
covered by thick foliage above, heavy rains cannot knock them
from the trees.
They are positively chemotropic to a spray of citrus leaves
placed in the wire-gauzed cage with them, immediately coming
to eat it. But if a spray of mulberry or willow leaves is sub-
stituted, they never touch it.
If a male and a female are kept together in a cage, they can
be seen to touch each other with their antennae. But, if an
extra male or female is added to the cage, fights are sure to
occur. As a result, they are often seen with their legs and
antennae broken away.
There are several points in the adult stage which may be made
clear in the following paragraphs:
a. The Emergence of the Adults. The adults were seen to
emerge on sunny days, in the early morning or in the middle
of the day, but never in twilight or darkness, nor on rainy days.
b. The Occurrence of the Adults. They occur from the last
part of May to the first part of August, but more abundant in
June and July.
c. Mating of the Adults. They mate once or twice nearly
every day. Each mating may last about one hour.
d. Oviposition. The females do not oviposit soon after
mating. The pre-oviposition period is rather long, about 1-2
weeks. Before ovipositing, the female makes a T-shaped slit
on the bark in the basal portion of a citrus trunk with two cuts

THE FLORIDA ENTOMOLOGIST

by means of its mandibles, and then deposits one egg in the slit
under the bark. A female oviposits about ten eggs during its
life.
e. Longevity of the Adults. The average number of days,
the adults, collected and reared in cages in the summer of 1940,
lived, was 28 days. The two adults lived for 30 and 28 days
respectively. The adults which emerged in the summer of 1941,
also lived for 25 days to 38 days.
f. Fecundity. Fecundity should include the number of eggs
left in its abdomen. The average number of eggs each female,
collected and reared in the cages in the summer of 1940, de-
posited and left in its abdomen is 15, and that of one female
was 8. (See Table 2.)
In the opinion of the writer, the number of eggs each female
can reproduce depends upon the size of its body. For example:
one female, with a body length of 24 mm., laid 6 eggs and carried
2 when dissected, that is 8.
Therefore, the fecundity of females may be considered as
varying from 8 to 20, or a little more than 20.
5. LENGTH OF LIFE. This species takes about one year's
time to complete its life cycle. The lengths of the different
stages of this species are shown in Table 3.
6. HOST PLANTS. The larvae have been collected from the
roots and the bases of the trunks of (i) Citrus sinensis, Osbeck,
(ii) C. tangerina, Tanaka, (iii) C. limon. Burn var. Eureka, (iv)
C. grandis, Osbeck, (v) Salix babylenica, L., (vi) Pyrus malus,
L.; and also from the upper portion of the trunks of (vii)
Fraxinus americana, Linn., and (viii) Pinus masseniana.
The adults have been collected from citrus trees (i-iv) and
big willow trees, (v) ; but not from apple trees (vi). The larvae,
collected from the roots and bases of trunks of apple trees, are
still being reared in our laboratory, to see what sort of adults
will emerge next year.
The larva, collected from the crotch between the trunk and
a thick branch of an ash tree (F. americana, L.) and that picked
out of a piece of pine firewood, (Pinus masseniana) are very
similar to those of this species; but since the parts attacked
by them are quite different from those by the larvae of the
citrus species, their identity remains to be determined.
The adults have never been seen to do any damage to trees
other than the leaves, petioles, and bark of citrus trees. From
the facts mentioned in the above three paragraphs, the host

VOL. XXVII-No. 4

TABLE 3.-SHOWING THE LENGTHS OF THE DIFFERENT STAGES OF
Melanauster chinensis Forster.

Larval Pupal |
Date of Stage Stage Date of
Egg Egg Stage (Including (Including Adult Adult
Deposition Hiber- Pre-Adult Emer- Stage
nation) Stage) gence
about
1 to 3 1 to 10 1 and 1/2 one
months months months ] month
Egg depos. June 13-20 June 25- April 23- June 8, June 8-
in C. tang. to July 4 June 7, 1940 July 6,
June 25- 1939, to 1940 1940
June 13-20, July 4, April 22, (female) 28 days
1939 1939 1940
Egg depos. June 13-20 June 25- April 20- June 8, June 8,
in C. tang. to July 4 June 7, 1940 July 8,
June 25, 1939, to 1940 1940
June 13-20, July 4, April 19, (male) 30 days
1939 1939 1940

Egg depos. May 30, I Preserved
in C. sinen. 1941 after
emer-
June 10- (male) gence
July 2,
1940
Egg depos. June 26- July 18, May 2, June 17, June 17-
in C. tang. July 18, 1940 1941 1941 July 13,
1940 to to 1941
June 26, May 1, June 16, 26 days
1940 1 1941 1941 (male)

CONTROL
Before control measures can be made clear, the writer wishes
to call the attention of her readers to the facts that (1) the
larval stage of most species of insects, whether a leaf eater or
a wood borer, is the stage that does the damage, while the adults
may or may not be; and (2) the larvae of leaf eating insects,
which do damage to the foliage of trees, are usually exposed,
while those of wood-boring insects, especially those of Ceramby-
cids, almost always live concealed in the depths of wood with
very good means of self-protection. So it is obvious that the
common methods of control for combating leaf-eating insects can
seldom be applicable for the control of wood-borers.
The larvae of leaf-eating insects can be controlled by collect-
ing them in large quantities or by exposing them to insecticides,
such as stomach poisons or contact poisons, by means of spray-
ers or dusters; while with the larvae of wood-boring insects,
they cannot easily be collected or killed with insecticides. Spray-
ers and dusters are almost useless things for entomologists
against wood-borers. Therefore, how to control this species
of citrus-root-cerambycid (Melanauster chinensis, Forster), both
the larvae and adults of which do damage to the trees, is not as
simple a question as thought by some entomologists in the East,
but a rather difficult problem to be solved.
Since citrus are very valuable fruits and the raising of them
is an important industry, the control of this fatal pest to citrus
trees is of great importance. From the very beginning, the
writer had planned to find out the weak point or points in its
life cycle. Several months later, after she had observed the
food-habits, damage, mating, and oviposition of the adults, and
hatching and tunneling under the bark, of the larvae, she began
to be able to set a few questions as an outline for her plan of
control. The questions are:
(1) How to kill the adults so that they cannot do damage
to young citrus trees?
(2) How to prevent the adults from depositing eggs under
bark of basal portions of citrus trunks? and
(3) How to kill the larvae before they bore into the wood?

As mentioned above, the study of its life history has been
repeated twice. Through her two years' study, it is very fortun-
ate that the writer was able to find out the most important weak
point in its life cycle. This is the deposition of eggs under bark

VOL. XXVII-No. 4

and the tunnelling of the young larvae under bark for a period
of about two months. The deposition of eggs under bark can
be discovered by any untrained workman if he is able to make
some observations; but the tunnelling of the young larvae under
the bark is the most difficult part to stdily and had never been
studied before by any entomologist either in China or in the
Japanese Islands. This is shown by the fact that the methods
of control of this species suggested by some entomologists in
the East, such as Sho Takahashi and some others, are simply
fictional, without being based on a study of life history.
For studying this particular point, i.e., the period of young
larval stage under bark, the writer often visited the citrus or-
chards in the Hwayang suburbs in the summer and autumn
months (June-November) of 1939 and 1940, in searching for
the larvae.
In every citrus orchard she visited, she looked for the exuda-
tion of frass and wood dust in the citrus trunks, from top to
base. When any exudation was found, she taught the workman
to chisel little by little and trace the groove further and further.
All the larvae found on the trunks belonged to another species;
all those found in the basal portions of the trees belonged to
this species.
The larvae found under bark in the basal portions of citrus
trunks were all smaller ones (5-16 mm. long) and those found
in the trunk were all larger. When any larva still remained
under the bark it was easy to find. By chiselling and paring
of the bark, very soon the half-formed gallery appeared and as
paring went on further and masses of packed wood dust had
to be removed, finally the entire half-formed gallery began to
be exposed, as shown in the text-figure 3, b., and the larva could
be extracted uninjured. The half-formed gallery is not easily
described. It is not straight but extends partly upward and
partly downward, partly broad and partly narrow, and branch-
ing this way and that, and surrounding the base of the tree in a
spiral direction. A young citrus tree, say about 5 or 6 years
old, is bound to die after the bark of the basal portion of it is
thus destroyed, by even one larva of this species. (See text-
figure 3, b.)
If the larva had already bored into the wood, difficulties
began. If the burrow in the wood was still short and very near
to the surface, chiselling little by little could sometimes enable
it to be hurt or unhurt. If the burrow was deeper, or so deep

THE FLORIDA ENTOMOLOGIST

that it had already gone down to the root or even rootlets, it
was hopelessly lost, unless the tree could be uprooted, sawed,
and split.
All the living ones, brought back to the laboratory, were
colonized, either in segments of branches or in the basal portions
of the citrus trees, one in a piece to see how long they would
stay under bark. The results obtained from these collections
were compared with those obtained by studying the life history
of this species in cages, and were found to agree very well.
Finally, it was established clearly the period of the young larval
stage under bark is about two months.
Based on this discovery, we can be sure that the earliest
hatched larvae (in June) would bore into the wood in August;
and those hatched last (in August) would bore into the wood
in October. To prevent the larvae from doing much harm to
the basal portions of citrus trunks, they should be killed as
early as possible. But, when they are very small, it is rather
difficult for inexperienced workers to find them. Therefore,
the writer wishes to suggest that the best period for killing the
larvae, before they bore into the wood, is from the first part of
July to the first part of October. This is, indeed, the key to the
whole situation, because it not only answers the third question
in the outline (page 90), but also helps to solve the first and
second questions indirectly, as discussed more fully under the
sub-heading 2, Methods of Control.
Before the key to the whole situation had been acquired, the
following preliminary tests were made, one after the other,
(i) trying to kill the larvae (borers) in the wood, (ii) testing
the efforts to kill the adults with poisons, and (iii) trying to
prevent the females from depositing eggs under the bark.
1. TRYING TO KILL THE LARVAE IN THE WOOD
Many citrus growers in Hwa-yang, Kin-tan, and Kiang-tsing
believe that heads of matches placed in the bores made by the
larvae can kill them. Some entomologists of the Japanese Is-
lands also suggested a similar means for killing the larvae. Of
course, the writer wished to try this method first.
On November 15, 1939, some frass and wood dust were seen
piled up at a small bore on a thick branch of a lemon tree in the
orchard on the college grounds. From the color and the condi-
tion of the frass and wood dust, it was evident that they had been
exuded inside of 2 or 3 days. This lemon tree has three very

VOL. XXVII-No. 4

low branches. One particular branch made an acute angle with
the ground, and the crotch was only about 2 inches from the
ground.
Before applying any insecticide, the frass and wood dust
was first cleaned from the bore and the portion of the burrow
extending downward was explored with a pair of forceps and
cleaned up also. Then a brass hook was thrust into the burrow
expecting to hook out a borer from it. But, no borer was found.
So it was thought that the borer may have burrowed much
further down. The lower end of the portion of the burrow ex-
tending upward when explored with the tips of a pair of strong
forceps, was like a sold mass, so this portion of the burrow was
overlooked.
After the bore and the descending portion of the burrow
had been cleaned up, 5 puffs of freshly prepared pyrethrum
powder were blown into this portion with a copper blower,
plugged tightly with cotton, and sealed with cold wax.
On December 2, 1939, this branch was sawed off, split, and
examined. As the result, a living borer of this species, whose
body length was about 25 mm. was found within the ascending
portion of the burrow, which was separated from the lower por-
tion by a plug of wood dust, which was pressed so tightly with
a secretion (probably from its mouth) that a pair of strong
forceps could not easily pick it away. The length of this ascend-
ing portion of the burrow was about 85 mm., that of the descend-
ing portion about 50 mm. and that of the plug about 70 mm.
The plug was made so air-tight that it was believed that no
odor of the pyrethrum powder could reach the borer. This
method of self-protection by the borer of this species (text-figure
3, f) has shown very clearly that this sort of attempt to kill
the borers is simply a failure.
2. ATTEMPTS AT KILLING THE ADULTS WITH POISONS
On June 1, 1940, 2 pairs of adults were placed in 2 small wire
cages, each of which was supplied with 2 pieces of citrus seg-
ments, whitewashed with quick-lime paste and a spray of citrus
leaves daily. They were observed several times daily. It was
found that the adults ate the leaves and bark of the citrus sprays
every day, but never touched the whitewashed segments. After
3 days, no more citrus sprays were supplied; but the adults still
never touched the whitewashed segments.
On June 6, a fresh citrus-branch-segment was whitewashed
with the same quick-lime paste. When it was dry enough, an

THE FLORIDA ENTOMOLOGIST

adult was held between the thumb and the index finger at the
bases of its elytra, and pressed gently against the whitewashed
segment for about 5 minutes. The adult began to open and shut
its mandibles so often that some of the lime paste was taken into
its mouth. After 5 minutes, it was returned to the cage, and
supplied with a spray of citrus leaves. This was repeated with
each of the 4 adults. Three adults died in 4 days and 1 died in
6 days.
The same trials were repeated with another 2 pairs of adults
in exactly the same way except that the composition of the
whitewash was a mixture of quick-lime and sublimed sulfur.
The adults all died in 2-3 days.
The same trials were repeated with another 2 pairs of adults
in exactly the same way, except that the compositions of the
whitewash was a mixture of quick-lime and calcium arsenite.
The beetles all died in 2-3 days.
The same trials were repeated with another 2 pairs of adults
in exactly the same way, except that the composition of the
whitewash was a mixture of quick-lime and arsenious oxide.
The beetles all died in 2 days.
From the results obtained here (Test II), it can be asserted
that after the basal portion of any citrus trunk has been white-
washed with any of the 4 kinds of paste, if any adult should
be "bold" enough to gnaw at the bark to make an incision, it
will surely die very soon.

3. PREVENTING THE FEMALES FROM DEPOSITING EGGS UNDER
BARK
In a cage with a pair of adults, the citrus-branch-segment,
whitewashed with simple lime paste, was not touched by the fe-
male beetle, even though it had deposited 6 eggs in the C. tang.
and again 6 eggs in another citrus segment.
In the cage of the Fifth pair of adults (see Table 1), the
trunk of the C. grand. was whitewashed with simple lime paste
to a height of 20 inches. For the first 16 days, the female did
not deposit even a single egg in it. But, after heavy rains on
June 27, 29, 30, and July 1, which washed away the paste at
some places near the lower portion of the trunk, 3 incisions
were found and 3 eggs had been deposited in them.
In the cage of another pair of adults, the trunk of the C.
sinen was whitewashed with lime-sulfur paste to a height of
20 inches and that of a C. tang. with lime-calcium arsenate to

VOL. XXVII-No. 4

a height of 18 inches. For 31 days, not a single incision was
made on either of the two trees, although 15 eggs in toto had
been deposited in 5 citrus segments.
In the cage of another pair of adults, the trunk of the C.
tang. was whitewashed with lime-arsenious-oxide paste to a
height of 8 inches. For 36 days, not a single incision was found
on the trunk, although 2 eggs had been deposited in willow
segments, three in a mulberry segment and 1 in the trunk of the
C. grand.
These tests have shown clearly that (1) after the borers
have once entered the wood, if their whereabouts are definitely
known they can be killed by hooking out without any need of
insecticides; but if their whereabout are not definitely known
their method of self-protection can foil any attempt at killing
them with insecticides; (2) the four kinds of whitewash pastes
are all offensive to the chemical sense-organ of the adults, and
of the four the lime paste seems the weakest and the lime-
arsenious-oxide the strongest; and (3) whitewashing of the
basal portions of citrus trunks can protect them from attempts
of the females to cut slits for the deposition of eggs.
While the tests for controlling this species were being carried
along in her laboratory and on the college campus, the white-
washing of (1) a portion of her own citrus trees on the campus,
(2) those in the Lion-Hill citrus orchard, and (3) those in the
seven citrus orchards of private citrus growers at Sze-tzu-ling
in Hwa-yang suburbs was being carried forward. In addition,
the control tests for the citrus trunk cerambycids were also made
in the same seasons. Therefore, her work in the summer
and autumn of 1940 was the heaviest of all other years. More-
over, it must be remembered that the alarms of air-raids and
cruel bombings from our beastial enemy were the most numer-
ous in Chengtu from May to November, 1940. It was fortunate
that the writer was not killed by those bombings. She is very
happy that she is now able to write a paper on the results of her
study for the benefit of her own country people who raise citrus
fruits, and at the same time, she wishes that it may be of a little
use to our American friends who cultivate even more citrus
fruit than we do.
Since chemicals from abroad were not available during our
war of resistance, the writer made up her mind to try all local
materials, such as quick lime, sulfur, calcium arsenate, and
arsenious oxide for her tests. Since lime alone seemed not strong

THE FLORIDA ENTOMOLOGIST

enough, she chose the two formulae: (1) quick-lime and sulfur,
and (2) quick-lime and arsenious oxide for all the following
practical experiments:
EXPERIMENT I.
Whitewashing of Lieu's Citrus Trees. For the use of "coloniz-
ing" the borers of different species of citrus cerambycids, the
writer bought some two hundred citrus trees of different ages
(2-3 years, 5-6 years, 11-12 years, and 15-16 years) within three
years, 1939-1941, and had them planted on several small pieces
of ground on the college campus.
On June 9, 1940, she chose the citrus trees on a small piece
of ground for tests. There were 14 in all, some were 11-12
years old. She had the tree trunks completely whitewashed with
the formula for controlling the species first. When the white-
wash paste had dried she had the basal portions of 7 citrus
trunks whitewashed with the quick-lime and sulfur paste and
another 7 with the quick-lime and arsenious oxide paste (text-
figure 4, a).
Results. The bark of the basal portions of the 7 citrus trunks,
whitewashed with the formula (2), quick-lime and arsenious
oxide paste, looked somewhat dry; while those with the formula
(1), quick-lime and sulful paste, were uninjured, as examined
two weeks later.
EXPERIMENT II.
Whitewashing of the Citrus Trees in the Lion Hill Orchard.
In this orchard, there were some three to four hundred citrus
trees of 20-30 years of age. The writer chose 50 of them for
experiments. On June 15, 1940, the trees were first whitewashed
with the formula for controlling Melanauster chinensis, Forster.
When the whitewash was dry, she had the basal portions of the
trees whitewashed with the formula of quick-lime and sulfur
paste.
Results. These citrus trees were examined 2 weeks later,
and it was found that the basal portions of these citrus trunks
whitewashed with the quick-lime and sulfur paste were normal,
and not a single incision was found; while the trees, not white-
washed, in the same piece of ground had many incisions made at
their basal portion.
EXPERIMENT III.
Whitewashing of Citrus Trees at Sze-tzu-ling in Hwa-yang

VOL. XXVII-No. 4

Suburbs. Sze-tzu-ling is the citrus center of Hwa-yang-hsien
and is about 20 lis (equal to 6-7 miles) from this college. There
are many private citrus orchards, large and small. Although
the owners suffered some losses from these cerambycid borers,
they had never realized the causes of the damage. Moreover,
they were not familiar with the manner of whitewashing.
Through many attempts the writer obtained permission of 7
owners, to use 10 citrus trees in each orchard for experiments.
These seven orchards were not near together. The whitewashes
were applied there during the first part of July 1940. Since
the whitewash for combating this Melanauster chinensis, For-
ster, is comparatively much easier, two more boys employed
besides the workman Wang-soo-yuin were sufficient for the work
to be done.
In each orchard, the 10 healthy citrus trees were evenly
divided by the writer, into 2 groups, A and B. They were
cleaned of any dirt and whitewashed by the boys.
The formulae used for whitewashing in the seven orchards
were of two kinds, viz: (1) quick-lime and sulfur, and (2) quick-
lime and arsenious oxide. The ingredients for each formula
were all weighed by the writer in her laboratory, and the mixing
of the ingredients in the field was also done by her own hands.
The trees in group A were treated with the quick-lime and
sub-limed sulfur; those in group B with quick-lime and arsenious
oxide. In each case it was applied to a height of about 33 cms.
or one foot.
Results. From the first part of August to the mid part of
October, 1940, three inspection trips were made to each of the
seven orchards. Each time an inspection was made in an or-
chard, 5 healthy and unwhitewashed trees, in addition to the
5 trees of Group A and the 5 trees of Group B, were examined
for egg incisions at their basal portions. Altogether, 35 healthy
and unwhitewashed citrus trees, 35 trees of Group A, and 35
trees of Group B were examined. The results were:

35 Trees of Total No. of Egg Slits Condition of Bark
at the Basal Portions at the Basal Portions
Group A 0 Normal
Group B 0 Slightly dry appearance
Healthy and un-
whitewashed 53 Poor

THE FLORIDA ENTOMOLOGIST

After having made a careful and continuous study of its
biology and control for about 2 years, accompanied by a series
of tests and practical experiments, the writer began to be able
to give the methods of control of this species, Melanauster
chinensis, Forster, as follows:
METHODS OF CONTROL. The methods of control include 3
steps; 1, killing of the adults; 2, killing of the eggs and the larvae
while under bark; and 3, whitewashing of the basal portions
of trunks.
1. KILLING OF THE ADULTS
Period of Collecting. Examine the basal portions of the
trunks and at the summer shoots of citrus trees, and kill all seen.
2. DESTROYING OF THE EGGS AND THE LARVAE WHILE UNDER
BARK.
Two or three times each month from the first part of July
to the first part of October of each year.
Examine the basal portions of the trunks (up to a height of
1 foot) for egg slits and exudations of wood dust and frass.
If there is any egg slit, pressing on it with the thumb should
smash the egg. If there is any exudation of wood dust or frass,
pare off the bark little by little to look for the young larva and
kill it. If this is thoroughly done, there will be no adults at all
the following year, and need to kill and prevent from depositing
eggs.
3. WHITEWASHING OF THE BASAL PORTIONS OF CITRUS TRUNKS
Period for Application. Choose a sunny day during the first
part of June.
Formula Chosen: Quick-lime ---.......--------... 10 catties
Sub-limed sulfur ..-------- 1/2 catty
Water -...---..-- ........-----------. 40 catties
Slake the lime in a vessel, large enough to contain the whole
mixture, with about 3 catties of water (preferably hot water)
until it has all slaked. If it is too thick, add another 3 catties
of water. Then add the sulfur little by little, while the lime is
boiling. Stir the solution slowly and evenly until it is well
mixed. Finally, add water to make the entire weight of the
mixture 40 catties, and continue to stir. This mixture is suffi-
cient for whitewashing 50-60 citrus trees of about 20-30 years
of age.

VOL. XXVII-No. 4

Method of Application. Before whitewashing, the basal por-
tions of citrus trunks should be swept clean, examined first to
make sure that not a single egg or larva is allowed to remain
there, and the bases should be cleaned of mud and swept clean
also. When the whitewash solution is ready apply it to about
one foot of the basal portions with a soft brush made of fibers
of the plant Abutilon theophrasti, Medic., as shown in the text-
figure 4, c. When the whitewash has dried the bases should
be covered up again with the mud which had been removed
before. This coating will remain for about two months, pro-
tecting the basal portions from deposition. These trees should
be inspected once a month. In short, it is suggested that any
one who has 1 or 2 hundred citrus trees should take steps 1 and 2;
and any one who has more trees or a larger orchard, may choose
to take steps 1 and 3. Our Government should do two things
to help the people to annihilate this citrus pest.
First decree that any citrus trees badly affected by the larvae
of this species should be uprooted, sawed, and split, in order to
kill all the grubs, pupae, and pre-adults in them; and as early
as possible, that an organization for the inspection of any citrus
trees, imported from any other localities, should be established.
As soon as the methods of control had been found, a booklet,
"Melanauster chinensis, Forster (Citrus root cerambycid)", was
written in Chinese by the writer for distribution to Chinese
citrus growers and published in April, 1941, by the Agricultural
Production Promotion Commission, Ministry of Agriculture and
Forestry.
SUMMARY
1. This species of citrus root cerambycids, Melanauster
chinensis, Forster, attacks citrus trees in both its adult and
larval stages. The adult eats the leaves, petioles, and bark of
twigs and branches, and of the trunks if the trees are very young.
The larva, immediately after hatching, feeds for about two
months in the green, sappy portion of the inner bark of the
basal portions of the trunks of citrus. When it has grown to a
length of 16 mm. to 20 mm., it begins to bore into the wood,
and seriously mines the trunk, the root, and the rootlets. One
larva of this species is able to cause the death of a citrus tree
up to an age of about 5-6 years.
2. It has one generation in a year. The adults appear from
the last part of May to the first part of August, but are most
abundant in June and July. They mate soon after emergence

THE FLORIDA ENTOMOLOGIST

and the pre-oviposition period may last for 1-2 weeks. The
females cut slits on the bark in the basal portions of citrus
trunks, close to the ground, and deposit eggs in these slits. The
eggs take 1-3 weeks to hatch. This species passes its egg, larval,
pupal, and pre-adult stages inside the tree for 12 months, more
or less, and then emerges as an adult, which lives in the open for
about one month or so. A female may deposit 10 eggs, more
or less.
3. While inside the wood, the larva protects itself very well
in its burrow, where no insecticide can reach it.
4. The larva grooves under bark for about two months.
This is the most important weak point in its life cycle.
5. Its only enemy is the ants in its egg stage. No parasite
has been observed throughout its life cycle.
6. The methods of control include three steps, namely:
A. Killing of the adults;
B. Crushing of the eggs and the larvae under bark; and
C. Whitewashing of the basal portions of citrus trunks.
7. Its host plants include not only all species of citrus trees
but also willows, apple trees and some others.

ACKNOWLEDGMENTS
To le R. P. O. Piel, the Director of Musee Heude, Shanghai,
and to Prof. G. P. Jung, Department of Entomology, College
of Agriculture, National Chung-shan University, the writer
wishes to express her hearty thanks for their foresight in help-
ing her to continue the study of wood-borers, the importance
of which nobody except them and the writer had ever foreseen
in China before our war of resistance broke out on July 7, 1937.
The writer wishes to take this opportunity to express her
deep appreciation and thanks to Prof. K. S. Sie and F. C. Woo
for their advice and suggestions regarding the new problem,
"Survey on the Citrus-Cerambycids of Szechuen and Experi-
ments for Their Control" (p. 63), which is very important for
combating these serious cerambycids, fatal to citrus trees, and
which is in line with her researches since the year 1933.
Sincere acknowledgments are due to Prof. C. W. Chang,
the Dean of the College of Agriculture, Nanking University,
Prof. K. S. Sie, and Prof. Y. Hsuwen Tsou, the former Dean of
the College of Agriculture, National Central University, for
their advice and encouragements in helping her to carry on
her work so far.

100

VOL. XXVII-No. 4 101

For carrying out experiments for the control of this species,
and for spreading information of control measures to citrus
growers in this country, the writer appreciates very much the
financial help rendered her by Mr. H. Y. Moh, the Chairman of
the Agricultural Production Promotion Commission, Ministry
of Agriculture and Forestry, Prof. C. M. Chiao, the acting
chairman, and Prof. F. C. Woo, the expert of the same.
In taking photos for her specimens of both the insects and
affected parts, she is very thankful to Messrs. C. C. Wu and
H. T. Tsing (correct spelling: Shi-tien Djin) for their kind help
and high technique.

CINARA OSBORNIANA nom. n.
A Correction
In the last number of the Florida Entomologist (Vol. XXVII,
pp. 43-54, published January 15, 1945) I described an apparently
undescribed species of aphid, giving it the name Cinara osborni
n. sp. I have now discovered (March 5, 1945) that I inad-
vertently overlooked the fact that Dr. G. F. Knowlton in 1942
described another species of Cinara under the same specific
name osborni. Cinara osborni Tissot clearly is a homonym of
Cinara osborni Knowlton. Because my recently described species
now stands without a valid name I here propose for it the new
name Cinara osborniana.
A. N. TISSOT

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VOL. XXVII-No. 4

THE DAMAGE OF MELIPOTIS ACONTIOIDES TO THE
ROYAL POINCIANA
J. R. WATSON
(Continued from last issue)
From the observations of Mr. Singleton at Key West, and
corroborated largely by a Mr. Phillips of St. Petersburg, we can
reconstruct some phases of its life history about as follows:
The caterpillar is a night feeder, retiring into the ground or at
least into trash around the base of the tree in the early morn-
ing, and ascending the tree again at night. If good hiding
places are provided, it may not necessarily go to the ground.
In an attempt to check the migrations up the tree, Mr. Singleton
banded some trees with a home made decoction somewhat similar
to "Tree Tanglefoot", which he placed on bands of heavy card-
board tied securely to the tree. He found when he removed
these bands that there were caterpillars under both the upper
and the lower edges-in other words, they had congregated there
on their way down and on their way up, and found protection
from light. That this was a pure light reaction was evidenced
in January, 1944, by the fact that at that time the pods on the
trees were cracking and opening and the caterpillars instead of
retiring to the ground in the early morning, simply crawled into
these pods. A box at the base of the tree also seemed to make
a very acceptable place to stay during the day. It is rather
peculiar that there should be any caterpillars on these trees in
January when normally a Poinciana is bare of leaves. But in
this case the trees had been defoliated in the late summer of
1943 and had put out fresh leaves in the late fall at a time
when the tree is usually shedding its leaves. It was on these
leaves that the caterpillars were feeding. That raises an inter-
esting question: How did the caterpillars "know" that there
was suitable food there? Ordinarily, under normal conditions,
there would be none. Under normal conditions there, it would
seem that the eggs do not hatch in January. Does the presence
of these young leaves give off some substance which causes
the eggs to hatch? It might seem fantastic at first glance, but
evidently this same thing does happen in the case of the tent
caterpillars on a wild plum. The time of leafing of a wild plum
will vary considerably from year to year with the variation of
weather but the eggs invariably hatch about the time the first
leaves appear. (To be continued)